This paper describes a technique for implementing the switch fabric of a high-speed router (with a throughput in excess of 600 Gb/s based on the current slate of the art), with the following properties. Delay performance is virtually identical to that of a standard output-buffered switch, and the switch fabric preserves the packet sequence, so that no resequencing is required for segmented packets. Clock rates are moderate except at ingress and egress points. This is achieved by distributing traffic across a number of crossbar switches operating at a low bit rate. The techniques used to resolve contention in the crossbar switches are described, and the bottlenecks limiting the capacity of the switch are discussed.